How much blood does it take to cause a reaction with two different types?

Blood type reactions occur due to the presence or absence of specific antigens on the surface of red blood cells. A reaction occurs when someone receives blood that contains antigens to which their immune system is not accustomed, leading to the production of antibodies that attack and destroy the transfused red blood cells.

However, it's important to note that the amount of blood required to trigger a reaction varies among individuals and depends on several factors, such as the person's immune system response and the concentration of incompatible antibodies. In general, multiple transfusions or repeated exposure to incompatible blood types may increase the risk and severity of a reaction.

Therefore, it's essential that blood transfusions are performed with compatible blood types to avoid potentially life-threatening reactions. Blood banks and medical professionals follow strict protocols and testing procedures to match donor blood with the appropriate recipients, ensuring blood transfusions are safe and effective.